1. Field of the Invention
The invention relates to a casing for the rudder machine of vehicle models such as model aircraft. The rudder machine, usually a servo-drive, is associated with the radio receiver of a remote controlling device.
2. The Prior Art
Due to the small size of modern servo-drives, they are installed in aircraft models as close as possible to the rudders, i.e., the servo-drive used for controlling ailerons for example is installed in direct proximity to the aileron in the wing.
The known servo-drives have a block-shaped configuration and are usually supported by rectangular mounting frames. Various fastening means are known for installing such mounting frames in the wing.
Installation frames into which the servo-drive is snapped or locked when installed are known from German design patent G 93 14 366.4, and those that have an additional means for securing the servo-drive in the frame via a screwed joint are shown in German design patent G 298 01 836.5. Like the servo-drives, frames of this type have a rectangular shape. Because such frames enclose the casing directly, they permit installation in minimized recesses having a rectangular basic shape. However, it has been shown that a recess cut into the wing in a cornered form will fracture under stress via one of the corners, because an increased notch effect is caused there.
In order to reduce or exclude such an effect, a round installation container in the form of a can has been proposed by DE 4205 129 A1. A rectangular servo-drive is fixed the can by an adapter insert via conventional holding bridges, and is supported there on the bottom part. The round container or can permits a continuous introduction of force and thus does not produce any predetermined breaking points. Furthermore, the round recess offers the advantage that it can be easily prefabricated via a round milling machine during manufacture of wings produced in series.
However, this solution has the drawback that a substantially larger recess must be cut into the wing because the can must enclose the conventional casing with its holding means for the upright installation, and is consequently clearly larger than the area or space occupied by the basic elements of a servo-drive.
It is an object of the invention to provide a casing for a rudder machine in such a way that the circular recess in the wing that receives the rudder machine can be as small as possible compared to the dimensions of the rudder machine.
This object is accomplished in that the frame is in the form of a circular cylinder, and the shells of the casing of the rudder machine or servo drive jointly form an aggregate having the approximate shape of a circular cylinder whose diameter approximately corresponds with the width of the frame.
For the installation of such a novel type of servo-drive, there is a mounting ring in which the servo-drive casing can be inserted in an exactly fitted manner. The mounting ring is glued into a round recess in the wing, which was produced by cutting or milling. The servo-drive can be subsequently inserted in the frame and can be fixed there via screws.
Since the servo-drive has to be fitted in the frame, which is glued into the wing, in an exactly predetermined position, it is useful to provide suitable guides on the frame and the servo-drive, for example a guiding groove and a guiding bridge exactly fitting in the groove, which assures that the servo-drive can be removed from the mounting ring after it has been installed, and that it will be automatically seated. again in exactly the same position in the mounting ring when it is reinserted in the frame.
The cylinder formed by the casing shells has an outer diameter approximately corresponding with the width of the frame. The plane of separation jointly formed by the shells of the casing extends parallel with the axis of rotation of the casing.
The shells of the casing are joined with each other by screws, rivets, glue or clips. The shells of the casing are joined with the frame by wedging, gluing, screwing and clipping.
At least one of the casing shells has a recess or opening within its radially outer side wall facing away from the plane of separation, so that an axis of swivel of the output arm of the servo extends approximately transversely in relation to the plane of separation, and the output arm is movable within this recess or opening.
In an alternative embodiment, the plane of separation jointly formed by the casing shells extends transversely to an axis of rotation of the casing.